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Crotchety Old Bastard
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2.2L MFI Build Question
Our shop is building a 911ST clone and the donor car is a 1971 2.2L MFI 911.
Question is how far can we expand the displacement of this engine? I'm thinking 2.5L would be a nice bump with high compression.
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RarlyL8 Motorsports / M&K Exhaust - 911/930 Exhaust Systems, Turbos, TiAL, CIS Mods/Rebuilds '78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar Brian B. (256)536-9977 Service@MKExhaust Brian@RarlyL8 |
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07-21-2017, 06:43 PM
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Under the radar
Join Date: May 2007
Location: Fortuna, CA. On the Lost Coast near the Emerald Triangle
Posts: 7,129
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How big? You mean with mostly standard Porsche parts, I guess.
My recently retired, (and for sale), motor was a 2,5 based on a 2,2 T motor. It used 2,7 Mahle 90mm P&C and the stock 66 stroke crank. The heads and case had to be machined for the larger cylinders. The heads also had to be chamfered for the larger pistons. The cylinder seating surfaces get thin, but it did not cause any problems with my motor over two decades of use. You could also install a 70mm (2,4 or 2,7) crank and rod set for a 2,7 displacement. You could also, ( I assume) install overbored 2,7 cylinders and go up to ( I think) 2,8 or 2,9.
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Gordon ___________________________________ '71 911 Coupe 3,0L outlawed #56 PCA Redwood Region, GGR, NASA, Speed SF Trackrash's Garage :: My Garage Last edited by Trackrash; 07-22-2017 at 02:59 PM.. |
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07-21-2017, 06:58 PM
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gearhead
Join Date: Nov 2007
Location: Loverland, CO
Posts: 23,522
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Yes. 2.4/2.7 crank and 1mm overbore. I think Henry at Supertec has done a ton of them.
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1974 914 Bumble Bee 2009 Outback XT 2008 Cayman S shop test Mule 1996 WRX V-limited 450/1000 |
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07-21-2017, 06:58 PM
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Crotchety Old Bastard
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Second question; what is the expansive capacity of the 2.2L MFI? Can it be adjusted to fuel 2.5L?
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RarlyL8 Motorsports / M&K Exhaust - 911/930 Exhaust Systems, Turbos, TiAL, CIS Mods/Rebuilds '78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar Brian B. (256)536-9977 Service@MKExhaust Brian@RarlyL8 |
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07-21-2017, 07:40 PM
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3 restos WIP = psycho
Join Date: Feb 2005
Location: North of Exit 17
Posts: 7,665
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85mm on a 66mm crank is the original config for an ST (2.3L). Later STs ran 2.5L in both short (66mm) and long (70.4mm) stroke. The MFI pump and lines are fully capable of supporting over 3L in displacement with space cam swap.
Sent from my Nexus 6P using Tapatalk
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- 1965 911 - 1969 911S - 1980 911SC Targa - 1979 930 |
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07-21-2017, 08:06 PM
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3 restos WIP = psycho
Join Date: Feb 2005
Location: North of Exit 17
Posts: 7,665
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Long stroke used 86.7mm pistons.
Sent from my Nexus 6P using Tapatalk
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- 1965 911 - 1969 911S - 1980 911SC Targa - 1979 930 |
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07-21-2017, 08:08 PM
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gearhead
Join Date: Nov 2007
Location: Loverland, CO
Posts: 23,522
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If you do short stroke the case will need to be machined to accept the big bore cylinders. Is the customer on with that?
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1974 914 Bumble Bee 2009 Outback XT 2008 Cayman S shop test Mule 1996 WRX V-limited 450/1000 |
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07-22-2017, 12:25 PM
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78 Porsche 911SC 3.0L, 3.3Turbo soon. 
My Garage
1971 Porsche 911
Baja Bug
